scsi: qla2xxx: Fix NULL pointer dereference for fcport search

commit 36eb8ff upstream.

Crash dump shows following instructions

crash> bt
PID: 0      TASK: ffffffffbe412480  CPU: 0   COMMAND: "swapper/0"
 #0 [ffff891ee0003868] machine_kexec at ffffffffbd063ef1
 Freescale#1 [ffff891ee00038c8] __crash_kexec at ffffffffbd12b6f2
 Freescale#2 [ffff891ee0003998] crash_kexec at ffffffffbd12c84c
 Freescale#3 [ffff891ee00039b8] oops_end at ffffffffbd030f0a
 Freescale#4 [ffff891ee00039e0] no_context at ffffffffbd074643
 Freescale#5 [ffff891ee0003a40] __bad_area_nosemaphore at ffffffffbd07496e
 Freescale#6 [ffff891ee0003a90] bad_area_nosemaphore at ffffffffbd074a64
 Freescale#7 [ffff891ee0003aa0] __do_page_fault at ffffffffbd074b0a
 Freescale#8 [ffff891ee0003b18] do_page_fault at ffffffffbd074fc8
 Freescale#9 [ffff891ee0003b50] page_fault at ffffffffbda01925
    [exception RIP: qlt_schedule_sess_for_deletion+15]
    RIP: ffffffffc02e526f  RSP: ffff891ee0003c08  RFLAGS: 00010046
    RAX: 0000000000000000  RBX: 0000000000000000  RCX: ffffffffc0307847
    RDX: 00000000000020e6  RSI: ffff891edbc377c8  RDI: 0000000000000000
    RBP: ffff891ee0003c18   R8: ffffffffc02f0b20   R9: 0000000000000250
    R10: 0000000000000258  R11: 000000000000b780  R12: ffff891ed9b43000
    R13: 00000000000000f0  R14: 0000000000000006  R15: ffff891edbc377c8
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 Freescale#10 [ffff891ee0003c20] qla2x00_fcport_event_handler at ffffffffc02853d3 [qla2xxx]
 Freescale#11 [ffff891ee0003cf0] __dta_qla24xx_async_gnl_sp_done_333 at ffffffffc0285a1d [qla2xxx]
 Freescale#12 [ffff891ee0003de8] qla24xx_process_response_queue at ffffffffc02a2eb5 [qla2xxx]
 Freescale#13 [ffff891ee0003e88] qla24xx_msix_rsp_q at ffffffffc02a5403 [qla2xxx]
 Freescale#14 [ffff891ee0003ec0] __handle_irq_event_percpu at ffffffffbd0f4c59
 Freescale#15 [ffff891ee0003f10] handle_irq_event_percpu at ffffffffbd0f4e02
 Freescale#16 [ffff891ee0003f40] handle_irq_event at ffffffffbd0f4e90
 Freescale#17 [ffff891ee0003f68] handle_edge_irq at ffffffffbd0f8984
 Freescale#18 [ffff891ee0003f88] handle_irq at ffffffffbd0305d5
 Freescale#19 [ffff891ee0003fb8] do_IRQ at ffffffffbda02a18
 --- <IRQ stack> ---
 Freescale#20 [ffffffffbe403d30] ret_from_intr at ffffffffbda0094e
    [exception RIP: unknown or invalid address]
    RIP: 000000000000001f  RSP: 0000000000000000  RFLAGS: fff3b8c2091ebb3f
    RAX: ffffbba5a0000200  RBX: 0000be8cdfa8f9fa  RCX: 0000000000000018
    RDX: 0000000000000101  RSI: 000000000000015d  RDI: 0000000000000193
    RBP: 0000000000000083   R8: ffffffffbe403e38   R9: 0000000000000002
    R10: 0000000000000000  R11: ffffffffbe56b820  R12: ffff891ee001cf00
    R13: ffffffffbd11c0a4  R14: ffffffffbe403d60  R15: 0000000000000001
    ORIG_RAX: ffff891ee0022ac0  CS: 0000  SS: ffffffffffffffb9
 bt: WARNING: possibly bogus exception frame
 Freescale#21 [ffffffffbe403dd8] cpuidle_enter_state at ffffffffbd67c6fd
 Freescale#22 [ffffffffbe403e40] cpuidle_enter at ffffffffbd67c907
 Freescale#23 [ffffffffbe403e50] call_cpuidle at ffffffffbd0d98f3
 Freescale#24 [ffffffffbe403e60] do_idle at ffffffffbd0d9b42
 Freescale#25 [ffffffffbe403e98] cpu_startup_entry at ffffffffbd0d9da3
 Freescale#26 [ffffffffbe403ec0] rest_init at ffffffffbd81d4aa
 Freescale#27 [ffffffffbe403ed0] start_kernel at ffffffffbe67d2ca
 Freescale#28 [ffffffffbe403f28] x86_64_start_reservations at ffffffffbe67c675
 Freescale#29 [ffffffffbe403f38] x86_64_start_kernel at ffffffffbe67c6eb
 Freescale#30 [ffffffffbe403f50] secondary_startup_64 at ffffffffbd0000d5

Fixes: 040036b ("scsi: qla2xxx: Delay loop id allocation at login")
Cc: <[email protected]> # v4.17+
Signed-off-by: Chuck Anderson <[email protected]>
Signed-off-by: Himanshu Madhani <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/scsi/qla2xxx/qla_init.c

@@ -591,12 +591,14 @@ static void qla24xx_handle_gnl_done_event(scsi_qla_host_t *vha,
 				conflict_fcport =
 					qla2x00_find_fcport_by_wwpn(vha,
 					    e->port_name, 0);
-				ql_dbg(ql_dbg_disc, vha, 0x20e6,
-				    "%s %d %8phC post del sess\n",
-				    __func__, __LINE__,
-				    conflict_fcport->port_name);
-				qlt_schedule_sess_for_deletion
-					(conflict_fcport);
+				if (conflict_fcport) {
+					qlt_schedule_sess_for_deletion
+						(conflict_fcport);
+					ql_dbg(ql_dbg_disc, vha, 0x20e6,
+					    "%s %d %8phC post del sess\n",
+					    __func__, __LINE__,
+					    conflict_fcport->port_name);
+				}
 			}
 
 			/* FW already picked this loop id for another fcport */